Near receiver having reed detector and having fluid diaphragm time delay control of alarm



Nov. 3, 1964 R. H. VOIGT 3,155,958

NEAR RECEIVER HAVING REED DETECTOR AND HAVING FLUID DIAPHRAGM TIME DELAYCONTROL OF ALARM Filed Jan. 29, 1962 2 Sheets-Sheet 1 INVENTQR. Robe/'2H. vo/gf Q T'TORNEYS R. H. VOlGT Nov. 3, 1964 3,155,958 HAVING ALARM 2Sheets-Sheet 2 NEAR RECEIVER HAV G REED DETECTOR AND FLUID DIAPHRAGM TDELAY CONTROL OF Filed Jan. 2-9, 1962 INVENTOR. Robe/"2 H. 1 0/92 W7 2i!15.5.

United States Patent 3,155,958 NEAR RECEIVER HAVING REED DETECTOR ANDHAVING FLUID DIAPHRAGM TIME DELAY CONTRGL 0F ALARM Robert H. Voigt,Milford, Mich, assignor to Aseco,

Incorporated, Milford, Mich, a corporation of Michigan Filed Jan. 29,1962, Ser. No. 169,463 9 Claims. (Cl. 340-310) This invention relates toelectrical control circuits for producing a delayed action andcontrolled duration audible alarm and more particularly to a receivinginstrument preferably designed to be used in homes, offices and otherbuildings as a component of the National Emergency Alarm Repeater (NEAR)system.

The task of providing a means of alerting the nation in the event of anenemy attack has been given by Congress to the Ofiice of Civil andDefense Mobilization. This organization has long recognized that somemeans had to be found to supplement outdoor sirens in providing moreeffective Warning since sirens often can not be heard indoors, and manysuburban and rural areas are not within the range of hearing of thenearest municipalsiren system. After considerable investigation andresearch it has been finally decided that what is needed is an indoorsystem which can be coordinated with the outdoor sirens alreadyinstalled.

Since such a system must reach the greatest number of homes andbuildings and still not entail undue costs, it has been decided to makeuse of existing electric power lines. Generating equipment will transmita signal in the form of a short burst of 270 cycles per second frequencysuperimposed on the 60 cycle power normally being transmitted throughthe power lines. A receiver unit which is plugged into an ordinary wallreceptacle will actuate a buzzer or bell upon receipt of the signal.

Certain safeguards must be built into the receiving component for thissystem to prevent false alarms. Means must be provided for delaying thesounding of the alarm for 10 to 15 seconds so that brief surges of powerwhich could be caused by lightning bolts, man made switching transientsand coded signals will not actuate the alarm. The timing means utilizedmust not be cumulative to short pulses since several lightning bolts orcoded signals of 2 to seconds duration each might accumulate to producea false alarm. The NEAR receiver must select a frequency of 270 cyclesplus or minus one cycle and reject all other frequencies. t must alsoreject a voltage amplitude of .5 volt R.M.S. or less. Additionall thereceiver must be inexpensive, probably less than $10.00.

It is an object then of the present invention to produce a reliablesignal receiving and alerting unit by providing a time delay switchingmechanism which provides a fixed time delay before setting off anaudible alarm and which operates independently of power line voltage,ambient temperature or relative humidity.

It is another object of the present invention to produce a receiving andalerting device for the NEAR system which will not be actuated bylightning bolts, switching transients or coded signals by providing atime delay switching mechanism which will respond only to a minimumsignal duration of to seconds.

It is still another object of the present invention to provide a NEARreceiving component which will not be cumulative to short pulses ofactuating frequency by providing a time delay switching mechanism whichwill reset almost immediately after it is die-energized.

Yet another object of the present invention is to reduce manufacturingcosts of a NEAR receiving and alerting component by providing a simplyconstructed time delay switching mechanism.

Still another object of the present invention is to insure theaudibility of the alarm actuated by the receiving component by providinga second time delay switch mechanism which independently controls theduration of the audible alarm after the requisite signal pulse has beenreceived.

A further object of the present invention is to produce a more reliableNEAR receiving component by providing a frequency selective circuitwhich will admit only a frequency of 270 cycles per second plus or minusone cycle and by providing a voltage amplitude selective circuit whichwill reject signals with a voltage level of less than .5 volt R.M.S.

Other objects and advantages of the present invention will be readilyapparent upon reference to the following drawings in which likereference characters refer to like parts throughout the several viewsand in Which FIG. 1 is a diagrammatic view of a preferred embodiment ofthe present invention.

FIG. 2 is a diagrammatic view of another preferred embodiment of thepresent invention.

FIG. 3 is a perspective view of a preferred embodiment with portionsremoved for purposes of clarity.

FIG. 4 is a perspective view of the components of thr preferred deviceadapted for connection within the preferred embodiment shown in FIG. 3.

FIG. 5 is an elevational View of a fluid cell of the present invention.

FIG. 6 is a cross sectional view taken substantially at line 66 of FIG.5, and

FIG. 7 is a view substantially like FIG. 6 but illustrating anotherpreferred fluid cell adaptable to the present invention.

Now referring to the drawings for a more complete understanding of thepresent invention, FIG. 1 illustrates diagrammatically a preferredreceiving unit as comprising an input line plug 1 adapted for insertioninto an ordinary A.C. current household wall receptacle (not shown) andhaving prongs 2 and 3. The prong 2 is connected to a rectifier 4 of anydesired type which rectifies the A.C. current (preferably volt 60 cyclecurrent) to a pulsating DC. current.

A neon lamp circuit indicated generally at 5 and a resonance circuitindicated at 6 are each connected across the plug 1 as shown. The neonlamp circuit 5 preferably comprises voltage divider resistors 7 and 8with a neon lamp 9 connected as shown. A small amount of energy thusflows through the neon lamp circuit 5 energizing the neon lamp 9,indicating that the receiver is connected into the supply line and thatthe voltage is at a suificient level for receiver operation.

A small amount of energy normally passes through the resonance circuit 6which preferably includes a capacitor 10 and an electromagnetic coil 11which form a series tuned LC circuit. The capacitive reactance of thecapacitor 10 would be approximately the same as the inductive reactanceof the electromagnetic coil 11 at the predetermined signal frequency,thus the reactances cancel one another and the circuit is resonant atthat frequency. The present frequency for the NEAR system is 240 cycles,but this frequency may be changed at some future date.

A resonance relay means 12 is disposed within the magnetic field of theelectromagnetic coil 11 and preferably comprises a normally open switch14 having one contact 14A fixed to a resonance reed 15 which is mountedat one end at 15A, with the other contact 14B being connected to the DC.side of the rectifier 4.

The resonance reed 15 is connected to an isolation relay circuit, asindicated generally at 16, comprising a o resistor 17 and a connectedcapacitor 18 which cooperate to form an RC filter network. Anelectromagnetic coil 20 is connected at one end to a point in the filtercircuit intermediate the resistor 17 and the capacitor 18, and

at the other end with the prong side of the plug 1. The capacitor 18 isalso connected with the prong 3 side of the plug 1. A normally openswitch 22 is disposed closely adjacent the electromagnetic coil 20 andhas a contact 23 operated thereby. The filter network as above describedoperates to partially filter out the DC. pulsa tions from the rectifier4 when the resonant relay circuit is actuated, so that the switch 22will remain closed. The switch 23 is connected with the DC. side of therectifier 4 while the other sWitCh contact 241 is connected with anelectromagnetic coil 26.

An armature 27 is disposed closely adjacent the electromagnetic coil 26and is operably connected to an axially movable pin 23. The pin 28 ispreferably spring loaded in the direction of the arrow to hold thediaphragm 29A of a time delay fluid cell 29 in a normally closed orexhausted position, the diaphragm 29A preferably being carried in aretaining cup 29B.

A normally open switch 31 is disposed between the fluid cell 29 and thearmature 27 and comprises normally spaced contact members 32, 33 and 34each carried on the end of spring leaf members 35, 36 and 37respectively. The leaf carrying the contact 32 is connected as shownwith the DC. side of the rectifier 4. The leaf 36 carrying the contact33 is connected with the prong 3 side of the plug 1 through anelectromagnetic coil 38. A clapper 39 is pivotally disposed near thecoil 38. The leaf member 37 is of a bi-metal construction, the twometals having different thermal characteristics and arranged such thatheating will tend to warp it toward the dotted line position shown. Athermal heater winding 40 is connected in parallel with the coil 38 andis disposed closely adjacent the leaf 37 as shown.

In operation, a small portion of the 110 volt 60 cycle current normallyflows through the neon lamp circuit 5. This flow energizes the lamp 9indicating the receiver is connected to a source of power of adequateamplitude. A small amount of energy also flows through the resonancecircuit 6 without energizing the electromagnetic coil 11 sufficiently toinitiate a response in the resonance reed 15.

When a signal of 270 cycles plus or minus one cycle of sufilcientamplitude is present across the plug 1, it passes through the resonancecircuit 6, causing the resonant reed 15 to vibrate at its naturalfrequency of 270 cycles per second. The reed 15 will swing in an arcsufficient to cause the switch 14 to open and close 270 times eachsecond. This will act to introduce a current flow from the DC. rectifier4, through the isolation relay 16. With the filter network partiallyfiltering out the DC. pulsations, the electromagnetic coil is energizedand will draw the contact 23 against the contact 24, thus closing thecircuit to energize the electromagnet 26 which in turn attracts thearmature 27. The pin 28 is thus moved away from the fluid cell 29, thusreleasing the holding force against the diaphragm 29A. The surroundingfluid (normally air) acts to slowly expand the diaphragm 29A, as will beexplained more fully below, causing the contact 32 to engage the contact33 and finally the contact 33 to engage 34. This is the means by whichthe required time delay from the receipt of the signal is produced.Preferably this time delay will be about 15 seconds.

As contacts 32, 33 and 34 engage, the heater winding 49 and theelectromagnet 38 will be energized. The clapper 39 will be vibrated tostrike the side of the housing 41 of the receiver or other adjacentstructure producing an audible alarm.

The alarm actuation signal of 270 cycles will normally be released after20 seconds, but it is necessary to provide means for continuing thealarm for a period of 40 to 60 seconds. As long as the contacts 32-33-34are engaged, the alarm will continue, and it will be seen that thecontacts 32 and 34 when closed, operate as a holding circuit, toenergize the electromagnet 26 independently of the resonant relaycircuit which opens on cessation of the 20 second actuation signal.

The bimetal leaf 37 will gradually be heated by the heater winding 40until the leaf 37 warps away from contact 33 thus breaking the circuit,deenergizing the coil 26 so that the pin 28 will immediately collapsethe diaphragm 29A. This opens the switch contacts 32 and 33, breakingthe alarm and heating circuits.

FIG. 2 illustrates a modification of the present invention in which aplug 102 is connected to a D.C. rectifier 104*. A normally open switch114 having one contact 114A carried adjacent a resonant reed 115 and theother contact 11413 carried on a leaf 114C pivotally mounted on a hairspring 114D.

The contact 114 is connected with the DC. side of the rectifier 104. Theleaf 114C is connected with an electromagnetic coil 126 and a contact134 positioned at the end of a bimetal leaf 137. An armature 127 ispositioned closely adjacent the electromagnetic coil 1% and carries anaxially movable pin 128. The pin 128 is positioned to hold a fluid celldiaphragm in a normally closed or exhausted position. Contacts 132 and133 are each carried at the end of leaf members 135 and 136respectively. The leaf 135 is connected to the DC. side of the rectifier10d and the leaf 136 is connected to a heater winding and a coil 111 ina resonance circuit 106.

The plug 102 is also connected to the resonance circuit 106 as shown,comprising a capacitor 110 and the electromagnetic coil 111. A neon lampcircuit 105 comprising a lamp 109 and a pair of divided resistors 107and 108 also is connected across the plug 102 as shown. A clapper 139 ispositioned closely adjacent the coil 111.

The embodiment illustrated in FIG. 2 operates as follows: The alarmactuating signal passes through the resonance reed 115 to vibratecausing the switch 114 to close. The hair spring 114D will be induced tovibrate the leaf 114C as the reed 115 vibrates thus producingnon-interrupting contact through the switch 114. This energizes theelectromagnet 126 causing the armature 127 and the pin 128 to move,setting into operation the slow expansion of the fluid cell diaphragm129. As the contacts 132433-134 engage the armature 127 is held inposition, the heater winding 1 10 is energized and a flow of current tothe electromagnetic coil 111 is maintained even after the actuatingsignal ceases. The coil 111 excites the clapper 139 and an audible alarmis sounded. The alarm continues until the heater winding 140 heats thebimetal leaf 137 sufficiently to cause it to warp, opening the contacts133 and 134 to break the current flow through the coil 126. The pin 128thus collapses the diaphragm 129 to separate the contacts 133 and 132breaking current flow to the coil 111 and the heater coil 140.

FIGS. 3 and 4 are views illustrating a preferred assembly of a NEARreceiver embodying the present invention. The box-like outer housing 41carries the clapper 39 and the electromagnet 38. The other elements arecarried on a fiat closure plate member 42 shown in FIG. 4. Inassemblingthe receiver, the housing 41 is positioned over the elementscarried on the bottom member 42 and screws (not shown) are insertedthrough the aligning holes 43 and 44 provided in the housing 41 and thebottom member lzrespectively.

FIGS. 5 and 6 illustrate the construction of the preferred fluid cell 29of the present invention. The fluid cell 20 comprises a diaphragm 29Aand the retaining cup 293. A spring 46 is seated in the retaining cup29B and urges the diaphragm 29A outwardly. A retaining ring 46cooperates with radially inwardly bent portions 47 of the retaining cup29B to seat the diaphragm 29A in the retaining cup 29B. The retainingring 46 is provided with an inwardly spaced linear edge portion 48. Thediaphragm 29A is provided with a perforation 49 which carries a wick 50extending inwardly into the diaphragm BA. The fluid cell 29 is normallyin a deflated position held thus by the pin 28 or 128 of FIGS. 1 and 2,the spring 45 being under compression. In being urged to this position,the linear edge portion 48 of the retaining ring 46 permits a portion ofthe edge lip of the diaphragm 29A to move away from the retaining cup29B as shown in the dotted line position of FIG. 6, in the nature of acheck valve, to permit the fluid in the interior of the diaphragm toexhaust. As the axial pin 28 moves away from the diaphragm 29A, fluid ispermitted to enter the diaphragm 29A through the perforation 49, thewick 50 providing the means by which entry of the fluid and thus theexpansion of the diaphragm 29A is delayed. The closeness of weave of thewick 50 will determine how fast fluid enters and thus will regulate thedelay interval.

FIG. 7 shows another preferred fluid cell 229 comprising a diaphragm229A, a retaining cup ZZflB, a spring 245 and a retaining ring 246. Apassage 250 communicates the space between the diaphragm 229A andretaining cup 22913 with the interior bellows 251. A needle valveassembly 252 adjustably regulates the flow of fluid through a bypasspassage 253. A spring biased ball 254 acts as a check valve permittingfluid to flow substantially freely from the passage 250 to the bellows151 but preventing reverse flow of the fluid. As the axial pin 28 movesto deflate the diaphragm 229A fluid moves through the passage 250 to thebellows 2S1 opening the check valve ball 254. As the pin 28 moves awayfrom the diaphragm 229A, the ball 254 prevents fluid from entering thepassage 250 without passing through the bypass passage 253. The needlevalve 252 can be adjusted to regulate the flow of fluid through thebypass passage 253 and thus regulate the time required by the diaphragm229A to expand.

In both modifications of the invention above described, it will be seenthat no accumulations of short duration actuation signals will operateto set off a false alarm, since when the resonance circuit is brokenprior to closing of the holding circuit, the armature pin willimmediately collapse the diaphragm and this resets the device to itsnormal position.

The components of the receiver are also inexpensive and the circuitry isnot very complex, lending itself well to printed circuitry manufacture,enabling costs to be held well below the figure which will make the NEARsystem readily available nationwide.

The system described accurately responds to the required close tolerancefrequency and amplitude range, rejecting all others, and incorporatesthe necessary delay feature without undue complexity which mightotherwise result in failures and/ or false alarms.

Although I have described but two embodiments of the present invention,it will be apparent to one skilled in the art that other changes andmodifications could be made without departing from the spirit of theinvention or the scope of the appended claims.

I claim:

1. In an alarm circuit having a source of electrical power and meansselectively imposing a predetermined actuation signal thereon, a delayedactuation device comprising (a) an alarm circuit including a switch andmeans producing an audible alarm upon actuation of said switch,

(b) means actuating said switch and including an energizing circuit anda time delay means,

(c) said energizing circuit being operable to actuate said time delaymeans upon receipt of said predetermined actuation signal,

(d) said time delay means being operable to actuate said switch upon thelapse of a predetermined time interval after the actuation by saidenergizing circuit,

(e) said time delay means comprising a fluid cell diaphragm beingoperable to urge said switch toward its actuated position as saiddiaphragm expands, means normally holding said diaphragm in a collapsedcondition, and said holding means being actuated by said energizingcircuit to release said diaphragm to expand whereby said switch isslowly urged toward a closed condition,

( a second time delay means operable to retain said holding means in areleased postion for a predetermined time interval after cessation ofsaid predetermined actuation signal, and

(g) said switch comprising a pair of closely adjacent contact members,and I (It) said second delay means comprising heating means provided onone of said contact members, means energizing said heating means uponsaid diaphragm being expanded a predetermined degree, and said othercontact member having heat responsive means operable to separate saidcontacts upon being heated a predetermined amount by said heating meanswhereby said switch is opened after a predetermined time interval.

2. in an alarm system having a source of electrical power and meansselectively imposing a predetermined actuation signal thereon, a delayedaction alarm device comprising,

(a) an alarm circuit including a switch and means producing an audiblealarm upon the actuation of said switch,

(1)) a resonance circuit including a capacitor tuned to the frequency ofsaid actuation signal and an electromagnetic coil,

(c) a resonance relay having a switch disposed closely adjacent saidelectromagnetic coil and being actuated upon receipt of said actuationsignal by said capacitor,

(d) a time delay means being energized by the actuation of said relayswitch,

(e) said time delay means being operable to actuate said alarm circuitswitch after the lapse of a predetermined period,

(f) holding means being operable to hold said alarm circuit switch inits actuated position for a predetermined time interval,

(g) said time delay means comprising a fluid cell diaphragm beingoperable to urge said alarm switch toward an actuated position as saiddiaphragm expands and means normally holding said diaphragm in acollapsed condition,

(h) said holding means being energized through said resonance relay topermit said diaphragm to expand,

(i) means urging said diaphragm toward said expanded condition,

(j) said diaphragm being provided with means permitting fluid to slowlyenter said diaphragm.

3. The system as defined in claim 2 and in which said holding meanscomprises,

(a) an axially movable pin and means normally urging said pin towardsaid diaphragm to urge same toward a collapsed condition,

(b) an armature operably connected to said pin, and

(c) an electromagnetic coil disposed closely adjacent said armature andoperable upon being energizeai to urge said armature toward said coilwhereby said pin is axially moved away from said diaphragm.

4. In an alarm system having a source of electrical power and meansselectively imposing a predetermined actuation signal thereon.

(a) a switch and a fluid cell actuator therefor,

(b) said fluid cell actuator comprising a casing having a fluid chamber,a diaphragm closing one side of said chamber, and spring meansresiliently urging said diaphragm toward an expanded position to acti'vate said switch,

(') means normally collapsing said diaphragm against the force of saidspring means to reduce the volume of said chamber,

(d) electromagnet means energized on receipt of said predeterminedactuation signal and operable when energized to remove said collapsingmeans from said diaphragm and allow same to be urged toward the expandedposition (e) means slowly admitting fluid to said chamber, and

(f) alarm means operated upon actuation of said switch following delayedexpansion of said diaphragm.

5. The system as defined in claim 4 and including means operable toactuate said collapsing means to return said diaphragm to said firstposition upon said predetermined actuation signal ceasing prior toactuation of said switch.

6. The device as defined in claim 5 and including holding means actuatedupon actuation of said switch and operable upon being actuated to holdsaidswitch in its actuated position for a predetermined time interval.

7. The system as defined in claim 4 and in which said fluid cellactuator further comprises,

(a) a retaining cup and said diaphragm member being secured to said cupto define said closed chamber,

(11) said spring means being carried by said cup and 8,, urging saiddiaphragm member outwardly with respect to said cup to urge said fluidcell actuator to wards said expanded position.

8. The device as defined in claim 4 and in which said fluid admittingmeans comprises a wick member disposed with one end in said chamber andthe other end exteriorly of said fluid cell actuator.

9. The device as defined in claim 4 and including valve means providedin said fluid cell actuator operable to open communication between saidchamber and the exterior of said fluid cell actuator only upon movementof said fluid cell actuator from said expanded position towards saidcollapsed position.

References Cited in the file of this patent UNITED STATES PATENTS1,205,731 Gerdien Nov. 21, 1916 2,339,025 Matthews Jan. 11, 19442,471,594 Weightman May 31, 1949 2,580,539 Goodwin Jan. 1, 19522,998,549 Meller Aug. 29, 1961 3,021,520 Weber Feb. 13, 1962 3,035,251Inderwiesen May 15, 1962 3,045,076 Gaylord July 17, 1962 FOREIGN PATENTS49,077 Netherlands July 16, 1940

1. IN AN ALARM CIRCUIT HAVING A SOURCE OF ELECTRICAL POWER AND MEANSSELECTIVELY IMPOSING A PEDETERMINED ACTUATION SIGNAL THEREON, A DELAYEDACTUATION DEVICE COMPRISING (A) AN ALARM CIRCIUT INCLUDING A SWITCH ANDMEANS PRODUCING AN AUDIBLE ALARM UPON ACTUATION OF SAID SWITCH, (B)MEANS ACTUATING SAID SWITCH AND INCLUDING AN ENERGIZING CIRCUIT AND ATIME DELAY MEANS, (C) SAID ENERGIZING CIRCUIT BEING OPERABLE TO ACTUATESAID TIME DELAY MEANS UPON RECEIPT OF SAID PREDETERMINATED ACTUATIONSIGNAL, (D) SAID TIME DELAY MEANS BEING OPERABLE TO ACTUATE SAID SWITCHUPON THE LAPSE OF A PREDETERMINED TIME INTERVAL AFTER THE ACTUATION BYSAID ENERGIZING CIRCUIT, (E) SAID TIME DELAY MEANS COMPRISING A FLUIDCELL DIAPHRAGM BEING OPERABLE TO URGE SAID SWITCH TOWARD ITS ACTUATEDPOSITION AS SAID DIAPHRAGM EXPANDS, MEANS NORMALLY HOLDING SAIDDIAPHRAGM IN A COLLAPSED CONDITION, AND SAID HOLDING MEANS BEINGACTUATED BY SAID ENERGIZING CIRCUIT TO RELEASE SAID DIAPHRAGM TO EXPANDWHEREBY SAID SWITCH IS SLOWLY URGED TOWARD A CLOSED CONDITION, (F) ASECOND TIME DELAY MEANS OPERABLE TO RETAIN SAID HOLDING MEANS IN ARELEASED POSITION FOR A PREDETERMINED TIME INTERVAL AFTER CESSATION OFSAID PREDETERMINED ACTUATION SIGNAL, AND (G) SAID SWITCH COMPRISING APAIR OF CLOSELY ADJACENT CONTACT MEMBERS, AND (H) SAID SECOND DELAYMEANS COMPRISING HEATING MEANS PROVIDED ON ONE OF SAID CONTACT MEMBERS,MEANS ENERGIZING SAID HEATING MEANS UPON SAID DIAPHRAGM BEING EXPANDED APREDETERMINED DEGREE, AND SAID OTHER CONTACT MEMBER HAVING HEATRESPONSIVE MEANS OPERABLE TO SEPARATE SAID CONTACTS UPON BEING HEATED APREDETERMINED AMOUNT BY SAID HEATING MEANS WHEREBY SAID SWITCH IS OPENEDAFTER A PREDETERMINED TIME INTERVAL.